Short birth interval and associated factors among women who gave birth in the last three years in Dembecha district, Northwest Ethiopia

Background Maternal and child mortality remains a major public health problem in Ethiopia. Improving short birth interval practice is a main strategy to reduce neonatal mortality, maternal mortality, adverse pregnancy outcomes, high fertility rate, and enhance economic development efforts. However, there has been limited study done regarding short birth intervals in the study area. Therefore, this study aimed to assess short birth intervals and associated factors among women who gave birth in the last three years in Dembecha district, Northwest Ethiopia, 2019. Method A community-based cross-sectional study was conducted among 880 reproductive-age multipara mothers using a stratified cluster sampling technique. The data were collected by face-to-face interviews through pretested and semi-structured questionnaires. Bivariable and multivariable logistic regression model was fitted. Variables with a p-value ≤0.05 were considered statistically significant factors. Adjusted odds ratio with a 95% confidence interval was used to report the association between predictors and the outcome variable. Results The prevalence of short birth interval was found to be 43.4% (95% CI: 40.2, 46.9). Husband education (able to read and write) [AOR:2.81,(95% CI:1.04,7.85)], wealth index (lowest quartile) [AOR:3.75,(95% CI:2.35,5.97), residence (urban) [AOR:3.20,(95% CI:1.62,6.33)],age at first marriage (15–17 years old) [AOR: 1.65,(95% CI:1.15, 2.26),and non-use of contraceptive [AOR: 8.78, (95% CI: 6.18, 12.47) were statistically significant variables. Conclusion The study revealed that the prevalence of short birth intervals among multipara women is found to be high. Husband education, wealth index, urban residence, age at first marriage, and non-use of contraceptives were variables significantly associated with short birth intervals. Hence, to overcome the problem the focus should be on increasing family planning utilization, avoiding early marriage, strengthening paternal education, and improving family income.

a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 Regional State, Northwest Ethiopia,350 km away from Addis Ababa, the capital city of Ethiopia, and 215 km away from Bahir Dar, the capital city of Amhara Regional State. The town has 4 urban and 31 rural kebeles, which are the smallest administrative units of the country. According to the population projection of Ethiopia from 2014-2017, for all regions, the total population of Dembecha district was estimated to be 151,023. Among these, 75,464 were females [18].

Sample size and sampling technique
The sample size was determined by a single population proportion formula by taking 51.2% proportion of short birth intervals from a previous study conducted in the Oromia region [6], a 95% confidence interval, 5% margin of error and design effect 2. The study subjects were selected by using stratified cluster sampling technique after estimation of targeted groups was done in the selected kebeles. Accordingly, the kebeles were stratified as rural and urban kebeles. Then proportional to size allocation techniques were used in determining the number of kebeles included in each stratum. Eight rural and one urban kebeles were selected using simple random sampling from 31 rural and 4 urban kebeles respectively. All eligible participants in the selected cluster were included in the study, making the final sample size 895. For 10 participants have failed to complete the questionnaire and 5 participants have refused to participate in the study, the response rate of the study was 98.3% and the final sample size was 880. A sample of 880 women of any of all marital statuses, between the ages of 15 and 49 years, with two or more children and whose last child was born within the last three years before the survey were included in the study, and women who have a history of abortion between the last child and index child, were excluded from this study.

Operational definitions
Short birth interval. Refers to an interval less than 33 months of a birth interval between the birth of the last child and the immediately preceding live birth to the mother [2,19].
Index child. It is defined as the child born immediately prior to a subsequent child [5]. Knowledgeable. Those respondents who scored at least 60% of the knowledge questions about a short birth interval correctly were considered knowledgeable [20].
Negative attitudes. Those respondents who scored above the mean in answering the attitude questions were taken as having a negative attitude towards a short birth interval [1].

Data collection instrument and process
Data were collected by face-to-face interviews using a semi-structured and pre-tested questionnaire which was first prepared in English and translated to Amharic and then translated back to English. Nine BSc midwifery degree holders were involved in the data collection while two MSc holders supervised the data collection process in each cluster. Before data collection, written informed consent was obtained from study participants who were over the age of 18 years. Whereas, for those participants who were under the age of 18 years, written informed consent was obtained from their parents/guardians and verbal assent was obtained from study participants for participation. Throughout the course of the data collection, regular meetings were held among the data collectors, supervisors, and the principal investigator. The collected data were reviewed and checked for completeness before data entry and the incomplete data were discarded.

Data analysis
The outcome variable for this study was a short birth interval. In this study, only the last birth interval was measured and the last birth was within the last three years to reduce recall bias. This was measured by assessing the length of time between the preceding birth and the current (last) birth. The participants' answers were categorized according to the WHO-recommended birth interval (33 months) and coded 1 if the birth interval was <33 months and 0 if the birth interval was �33 months.
The knowledge level of the respondents was assessed using 8 items. The respondents' level of knowledge about birth interval was reported as good knowledge if the study participants correctly responded to more than or equal to 60% of knowledge assessment tools. The attitude of respondents was assessed using 17 items and categorized as positive if they responded below the mean of attitude-related items.
Data were entered into Epi Info version 7.1.5.2 and exported to Statistical Package for Social Science (SPSS) version 20 for analysis. Bivariable and multivariable logistic regression was used to determine factors associated with short birth intervals. Variables with a P-value of less than 0.2 in the bivariable analysis were included in the multivariable logistic regression to adjust for possible confounders. A p-value � 0.05 with a 95% confidence interval for the adjusted odds ratio was used to determine the level of significance.

Ethics approval and consent to participate
Ethical clearance was obtained from the School of Midwifery under the delegation of the Ethical Review Board of the University of Gondar. A formal letter of cooperation was written to each selected kebeles by Dembecha district health office. Written informed consent was obtained from study participants who were over the age of 18, and assent was obtained from those participants who were under the age of 18, after they had been informed about the objective of the study. In the consent, statements about the potential risk, benefit, and confidentiality were included. Accordingly, the Ethics committee approval was obtained for this written consent.

Socio-demographic characteristics
A total of 895 mothers were eligible in the selected kebeles; from which, 880 participants responded or participated in the study, making a response rate of 98.3%. The median age of the respondents was 34 years with an IQR of 8 years. Half (50.1%) of the total participants had no formal education ( Table 1).

Reproductive characteristics of study participants
More than half (53.4%) of mothers were first married at the age of 15-17 years. A parity of four was seen in 525 (59.7%) of the participants. Four hundred eleven (46.7%) study participants have 3 or 4 alive children. More than half 465 (52.8%) of respondents delivered their index child in the age range of 20-29 years. Over 3/4 th (87%) of respondents had antenatal (ANC) follow-ups for the index child. Most of the respondents 590 (67%) delivered their index child at the health institutions. About 568 (66.9%) of the respondents breastfed their child for 24 months and above ( Table 2).

Knowledge and attitude of the participants
More than three fourths (87.2%) of the respondents had information about short birth intervals, and the main source of information for the majority (66.3%) of the respondents was health care providers. Among the respondents who have information on birth intervals, 67.3% of them mentioned that a short birth interval was considered when it was less than 33 months ( Table 3). From the total participants, 587(66.8%) were knowledgeable, whereas, 541(61.5%) respondents had negative attitudes towards short birth intervals ( Table 4).

Prevalence of short birth interval
The prevalence of short birth intervals was found to be 382 (43.4%) with 95% CI:(40.2,46.9) and the median birth interval of this study was 36 months with an IQR of 8 months.

Factors associated with short birth intervals
On bivariable analysis, maternal age, maternal occupation, husband education, residence, wealth index, duration of breastfeeding the index child, age at first marriage, maternal age at delivery of index child, family planning use before conceiving last child, the survival of index child and knowledge of the study participants were significantly associated with a short birth interval at a p-value <0.2. However, husband's education, wealth index, residence, age at first marriage, and non-use of contraceptives were the factors associated with the outcome variable in multivariable logistic regression. Accordingly, women whose husbands could only be able to read and write were 2.81 times more likely to have short birth intervals compared to those women whose husbands completed college education and above (AOR = 2.81;95% CI:1.01, 7.85). Likewise, being in the lowest wealth quartile was 3.75 (AOR = 3.75;95% CI:2.35, 5.97) times more likely to have a short birth interval as compared with those in the highest wealth quartile.
This study revealed that women who first married at the age of 15-17 years were 1.65 times more likely to have a short birth interval compared to women who married at the age of 18 years and above (AOR = 1.65; 95% CI:1.18, 2.31). Similarly, the odds of having a short birth interval was 3.2 times higher among urban residences (AOR = 3.2;95% CI: 1.62, 6.33) compared with rural residences. Moreover, women who did not use contraceptives were 8.78 times more likely to have short birth intervals as compared to women who used contraceptives (AOR = 8.78; 95% CI; 6.18,12.47) ( Table 5).

Discussion
This study tried to assess the prevalence and factors associated with short birth intervals among women who gave birth in the last three years in Dembecha district.  In our study, about 43.4% of women had short birth intervals (95% CI:40.2, 46.9). This finding is comparable with the study conducted in Debre Markos town which is 40.9% [21]. But, the finding of this study was higher than other studies done in Tigray, Ethiopia (23.3%) [9], Iran (28.5%) [22], and Bangladesh (24.6%) [19]. The possible reason for the discrepancy could be the difference in the selection criteria of the study participants and socio-cultural differences. The study in Tigray excluded mothers who had twin deliveries, preterm birth, and who didn't have birth certificate. Nevertheless, in this study, we excluded only mothers who had abortions between the last two deliveries. This might have increased the prevalence of short birth intervals in this study. In the case of the studies carried out in Iran and Bangladesh, there is a socio-economic difference from our study. The women in the aforementioned studies, in Iran and Bangladesh, were mostly educated and residing in urban areas contrary to our study, where the majority of the respondents were uneducated and rural residents.
This study's result was lower than the result of studies conducted in Hosanna (57.6%) [20], Oromia Illubabor zone (51.2%) [6], and Jimma (59.9%) [23]. This variation might be due to the difference in defining criteria of short birth intervals. The previous studies used 36 months as a criterion to define short birth intervals opposite to the current study which used 33 months as per the WHO recommendation, which might have relatively decreased the prevalence.
In this study, women whose husbands could read and write but had not completed primary or above level of education were 2.81 times more likely to have short birth intervals after the index child compared to those women whose husbands completed their college education and above. This finding is supported by a study conducted in Dabat district [5]. The possible explanation could be the fact that most of the decisions on the utilization of maternal health care services are made mainly by the husbands. If the husbands hadn't had formal education, they might not have known the consequences of short birth intervals and encouraged their wives to have many children within a short period [24].
Women residing in an urban area were 3.2 times more likely to have short birth intervals than women residing in rural areas. The possible reason might be that most rural women breastfeed their newborns exclusively for a longer period than urban women do. Hence, they might benefit from lactational amenorrhea. This reasoning is supported by a study conducted in Niger, which suggested that the median duration of exclusive breastfeeding was only one week amongst urban women contrary to two months among rural women [25].
Women from the families within the lowest quartile were 3.75 times more likely to have a short birth interval than their highest quartile counterparts. This finding is in line with the studies conducted in Arba Minch district in Ethiopia, Bangladesh, and Nepal [1,19,26]. The possible reason might be that children born from poor households are assumed to be a source of income for the entire household thereby leading to short birth intervals. This study showed that women who didn't use postpartum contraceptives after the index child were 8.78 times more likely to have short birth intervals compared to contraceptive users. This finding is supported by studies conducted in Oromia, south pastoral community, and Dabat district [5,6,27].
The age of mothers at first marriage had a statistically significant association with short birth intervals. This study revealed that women who married at the age of 15-17 years were 1.65 times more likely to have short birth intervals than women who married at the age of 18 years or above. Similar findings were found in the studies conducted in Bangladesh and Nepal [19,26]. The reason might be that women who married at the age of 18 years and above would have a better opportunity for getting information, and education. Besides, having more power in making decisions on future fertility and growing older might have resulted a decline in women's fecundity, which increases the time it takes to become pregnant.

Limitations of the study
This study acknowledged some important possible limitations that should be considered when interpreting the results. As some of the questions are sensitive, social desirability bias might be present, and since they responded to previous birth interval periods, recall bias might be introduced. There might be also a social desirability bias on the declaration of the sex of their child. Lastly, as the reported sex ratio is too low and the percentage of children who died is likely also too low, there could be an omission of male children who died.

Conclusion
Short birth interval practice is high in the study area. Factors like, women's husbands who can only be able to read and write compared to more education, non-use of contraceptives, women found in the lowest wealth quartile, first marriage at 15-17 years, and urban residence were significantly associated with short birth intervals. Therefore, actions should be taken to increase family planning utilization, avoid early marriage, and strengthen paternal education to reduce short birth intervals.
Supporting information S1